‘COST OF LIVING’ Two disabled characters and two caretakers make up the cast of Martyna Majok’s gripping play, directed by Jo Bonney for Manhattan Theater Club. But which is which? John, who has cerebral palsy, is a rich, bratty grad student; Ani, a double amputee, is a hilariously foul-mouthed North Jersey terror. The people who help them, Eddie and Jess, have different problems. “Cost of Living,” which could have been an identity play about people with disabilities, is thus so much greater: a play about disabilities with people.